SU1523317A1 - Method of hardening parts - Google Patents

Abstract

The invention relates to mechanical engineering and is intended for strengthening by surface plastic deformation of the local structural elements of the parts of the form of rotation bodies. The purpose of the invention is to improve the quality of processing by increasing the thickness and hardness of the hardened surface layer of the local structural elements of the parts. The body is reported to have a running in motion along the reinforced surface of the part. The part contacts the body through uniformly mounted machining bodies, the number of which is chosen from the range defined by the inequality: 0.135 ^. 10 ^-2. HB ^. D ^{3 _{≤A (1-2φ / Α D. N}} ) 2. SIN ² φ / N / B + COS ² φ / N≤10 ^{-2 HB.} D ³ , where: A = 2ϕ ^2. F ^2. MD ² (1 + B), B = 4J / MD ₁ I and M are the inertia moment and the body mass, respectively, N is the number of machining bodies, F is the oscillation frequency of the part, Α _D = 2ARCSIN _{(D 1 ^{/ D N SINφ / N.)}} , D ₁ - diameter of the circle tangent to the machining diameter of bodies D, D _N - diameter of the processed surface of the workpiece with Brinell hardness HB material. This allows an increase in the thickness and maximum hardness of the hardened layer, as well as an increase in the uniformity of the hardening of surfaces on the local structural elements of parts such as grooves and radius transitions, which are in the process of exploitation by stress concentrators.

Description

The invention relates to mechanical engineering and is intended to be strengthened by surface plastic deformation of local constructions. elements of details of the form of bodies of rotation.

The aim of the invention is to improve the quality of processing by increasing the hardness of the hardened surface layer of the local structural elements of the parts.

FIG. 1 is a schematic diagram of the processing method; ya fig. 2 is a graph of the dependence of the energy of the impact of the shell of the shell with the workpiece on the number of deforming bodies installed on it; in fig. 3 is a schematic diagram of an apparatus for carrying out the method; in fig. 4 is a section A-A in FIG. 3; in fig. 5 shows the arrangement of the machining bodies while strengthening the cylindrical surfaces in FIG. 6 - the same, when hardening conical surfaces; in fig. 7 - the same, when hardening curved surfaces.

On the detail of the shape of the body of rotation 1, the local structural element (grooves, radius transitions, etc.) facing the hardening freely install the shell of the wrapper 2, on which the rolling bodies 3 - rollers 3 are evenly spaced, their number is chosen from the range determined by by equality

27 0.135 -lO -HB-D A (1 - -) 2-S-

.

 B + cos - n

 lO -HB-D

(one)

A 2ir2f2niD2 (1 + B);

N. .

n - the number of processing

tel 3;

f is the frequency of oscillation of the part; m is, respectively, the moment of inertia and mass of the rolling device 2;

o (2arcsin (- sin -);

dL) n

D is the diameter of a circle tangent to the machining bodies with a diameter D;

D is the diameter of the workpiece surface with the hardness of the material according to Brinell HB (Fig. 1).

The machining bodies 3 are made, for example, in the form of steel hardened rollers with a diameter D, the hardness of which is higher than the hardness of the material of the hardened part 1. The rollers 3 are mounted on the grinding sheet with the possibility of rotation, the diameter of the circle tangent to the machining bodies being

D, D + 2D + 4A.

(2)

The diameter value D is selected from the condition of ensuring the maximum force of interaction of the body of the rolling-in 2 with the workpiece 1 with a stable mode of vibratory support of rotation of the rolling-in, which

according to experimental studies, it is realized if the inequality

Dn n, .D, +

2D + 4A.

Q j

0

five

0

five

40

45

50

55

The rollers 3 are mounted so that their plane of rotation is normal to the surface of the part 1 at the point of contact. Details 1 report circular oscillations in a plane perpendicular to its geometric axis, with a specific amplitude and frequency. Under the action of oscillations, the body of the rolling-in unit 2, which is freely mounted on its surface, is drawn into the running-in due to the effect of vibratory support of rotation. The contact body 2 is in contact with the surface of the workpiece 1 through the machining bodies — rollers 3. The contact with the surface 1 of each machining roller 3 during the rolling process of the annular rolling wheel occurs with impact, and the machining part 1 is on one side and ring roll with another. Impacting the body of the wrapper 2 with the workpiece surface 1 when it contacts them through the rollers 3 causes the material of the part 1 to be plastically deformed and strengthened at the points of contact with the machining rollers 3. The ellipsoid collision tracks have a roughness equal to the roughness of the polished machining rollers 3. The rotation of the ring body of the rolling unit 2 and the above arrangement of the rollers 3 ensure the overlapping of the tracks of the collisions along the entire surface of the workpiece 1. The processing time is determined in each specific case by experimental method depending on the physic -mechanical properties of the material of the workpiece 1 and the required parameters of the quality of hardening.

The number of machining bodies (rollers) is determined by the following. Chord H is common to the circumference of a part of diameter D and a circumference of diameter D, tangent to the machining bodies 3 (Fig. 1).

From LAOW

DI „. with

H 2 - „- i sin I D.sin / A In

de

n

the central angle of the circle, touching the machining bodies, formed by its radius, is carried out from the center to the points of contact of the part with two adjacent machining bodies.

From 4AO, B

Dr,. „Н sin -„ - -,

a 2

de c / is the central angle of the part formed by its radii drawn from the center of its cross section to the points of contact with two adjacent machining bodies. Consequently,

tr „. 2 (5 n 2

.11d

D.sin - D. sin - -n

from where

0 / 2arcsin (- sin -), Vdn

During the transition from contact of a part with one machining body to a contact with a neighboring body, the spinner will rotate around its axis by an angle yo1. The value of 5 o / is determined from the comparison of two adjacent positions of the rolling unit: tangent at points A and A, and tangent at points A and A.

Of l

o / j Lo / 2 2 2

as an additional angle to the angle equal to the sum of the two angles of the triangle not adjacent to it, whence

th

 - 2

 n

(3)

During the period of one oscillation of a part, the roll-in machine performs one movement of the running-in on its surface, coming to the beginning of the next period to the starting point and turning at a certain angle around its geometrical axis. Since the surface of the rolling wheel is intermittent due to the presence of gaps between adjacent machining bodies on it, then at the start of the next oscillation period de 3176

The hopper can come to the initial point of contact with the part by a conditional point on a circle tangent to the machining bodies and lying in the gap area. Enter the notation

J. 2f. og - from which -n 211, angle

rotation of the rolling wheel during the oscillation period can be expressed as follows:

, / l / i / f. 21f.2} f o (-, п Лс - (с / -,) -

15

 2.11 21G (1

0/3 n

Angular speed d

H

about

2 (1 - 7--)

 About / p :.

one

- where T - is the period of oscillation of the part with frequency f.

five

0

from where

2

(four)

s 2-irf .. ZiFfd - ---)

about about T p

C1

where fgg is the spin-in speed.

Let us make up the equation of the amount of motion of the rolling mill, introducing the system of rectangular coordinates of the HOU (Fig. 1).

Change in the amount of movement of the wheel on the X axis

 - fM - 0 /) S COS. .

35

(-) s, sin (/ -; i).

2 n

(five)

The change in the amount of movement of the wheel on the axis Y

(.

4-) -S sin4-) 2 nti2 n

(6)

where V and V,.,, respectively, S (-) Oo (J.)

the length of the center of the grinding wheel before and after the impact;

S and S are normal and tangential to the components of the momentum vector (product of the mass of the rolling device to its corresponding velocity).

The change in the amount of motion of the obstetric when rotating around its center of mass

715233178

I (to - U)) -fs cos (- -) - Multiplying the first equation by cos -,

  2 n. Before(

and the second to sin - and subtract the second from

S sinC- - dM (7) first, we get

D, .. V

where ω and, respectively, the angle ™ (-) f ™ 2 (2 speed of the rolling line to

and after contact with + 2l (- S

batyvakytsogo body with de- 102 (-12p

hoist.

We believe that in the process of a strike, de-Benefit by the known trigonometals does not slip by relative ororic relations for the sum of the treatment body, i.e. The tangent and normal coefficients of the momentum vector from the obtained JS I 4 f S (8) equations can be represented as.

where f is the coefficient of friction of the matter-D g / lof uJ}

Pas machining bodies 2 - T

material details.20

The average value of the angular fast-S ha ..- Hz)., SinCoT + -.-) -a ,,, sin -

Tie Roller / t-i 2

,, - littllliy, (9)

 Substitute the obtained values of S. and

25 S, /, to equation (11): Linear speed of the center of the running-in before and after the impact with the detail CK; ,,) y – i; (., Cos (o (+ - |)

. 2X o5s 10) L & d. . , do /. - -2- + а (4 (cos у W (., Sin (o (+ -2)

Taking into account (3), Eqs. (5) - (7) can

but present in the form: sin | + W (,,.

mV. sino - „- + -„ -;

 iAfter the transformation, we get the coLs / / Sot 35 ratio between the angular velocities mVoj (4) - mVop (. coso / sS cozy - -. before and after the impact

14, cos f - S, sin f).::, T | 1, „,

(11) (, T (-) - T (12)

Expressing linear velocity through 40If 7

angular according to (10), the first two

equations are represented as

Substitute the values of S and

m 2ico, .sino (S., sin-- + - -, (8), then the condition of non-slip2 2 45k of the rolling unit when it is run-in on

D, 3). C, the details will take the form

m m -W cosc S cos -,, “d.

   -CJ + i cos - -Y (., Cos (o +

- S sin. one

2 , a) ,. .) "T

MANKIVES first equation on sin -,

and the second on the owl - and folding them between

Marked in Eq. (12) with a set of COMBINATIONS (We obtain jjjj2

, 1 + -g cosot m) jSin "-sin -2- + m yw, cos - - 55 tel K, imagine

d

 m 2i u),, coso (-cos - „- S.system of equations (9) and (12) in the form

9 152331710

  “On the other hand, it is known that

1 is optimal from the point of view of increasing L () W (., 26Jp5 durability of parts is

surface hardening mode

Its solution is plastic deformation at

g d

2K 1 degree of work hardening with - -, satisfied Chi (- 24sY; K (°

  inequalities

We believe that the energy of deforming O 3 5 (15) Eu of the material being processed

the parts are equal to the impact energy, i.e. section imprint diameter on the machining of the kinetic energies of the rolling mill, the surface of the part to be washed,

before and after impact: processing bodies in a given

In this case, either a 1T IlSiw 2 diametre ball is assumed to be 2 2 hours - with nJ-ixР spherical roller dia Y 2 4 (-1 (L - 4 meters D. Assignment of the degree of work hardening below 0.3 non-target) (l) (, - W ( .,) (I + i), 20 times, because in this case it is not possible to fully increase the hardness

psh, glued surface. Increase

(- (v 4 (-1 degrees of work hardening to 0.5 accompanies iinj) 2c with an increase in the surface hardness of T + PCPS / g

4 - - jjjjj2 25 Further increase

  inD work hardening does not cause an increase in hardness and, therefore, from this point

vision is useless. Zevigde I + 5 - the moment of inertia of the impact energy of the impact when dynamic relative to the point of hardening of parts from hardness

contact with deformed-according to Brinell material by machining bodies. details of IW are recorded in the image. Here dependencies are used (9)

and (12). In view of (13) and (4), as well as 1 7 d

taking into account Q 0,17- -HB-D

IT

7 ff 1 rlL. Taking into account the boundary values of the degree of work hardening f (15), the maximum

f 1 +, cos is the value of hardening energy

 2-. 40.-g

 ,, 0.17 (0.5) -HB-D5 10 -HBH

After the transformations, the expression Ecker-g will have the minimum impact shock:

2ir2f2 (4n.mDf) mD (1 -) 0.1 7 (0.3) -NB-VZ 0.135-10 nB-03

hardening impact determined

41 + mD cos - Then the range of allowed energy

impact with control inequality

Q

sin - iwviH v - vMoKc

shsh50

2f,

E E „E,

E A (1 - ---), (14)

 in +

P ,

55 0.135-10 -HB-D3 i E., 610 -HB-D3

where a 2t2f2md2 (1 + b).

 Taking into account (12), we obtain (1).

g Y.-The limits of this inequality are defined ™, the properties of the material are treated. 15233

the workpiece (Brinell hardness) and the size of the machining rollers (diameter D). The impact energy (14) of the grinding wheel with the part depends on the mass of the grinding wheel, its moment of inertia and the number of deforming rollers. The minimum mass of the rolling wheel is determined constructively, based on the possibility of installing brane-sized rollers on it. The moment of inertia of the runner is related to its mass by the known dependence. Thus, at the chosen mass, inequality (1) defines the range of the optimal number J5 of rollers on the rolling-in wheel.

A practically optimal number of rollers is determined in this way. In accordance with (14), a graph is plotted.

the dependencies of E on n, with other known conditions, and on it are carried out two horizontal lines corresponding to the minimum E jii and maximum Borrowing levels of impact energy for the material of the workpiece. The projections of the points of intersection of the graph with these horizons on the axis n give the boundary values of the range of the optimal number of rollers on the rolling-edge. FIG. Figure 2 shows the graph of the impact energy of the rolling edge with the workpiece E versus the number of machining rollers installed on it, obtained from (14). The graph is plotted for the following processing conditions and parameters of the grinding wheel: the oscillation frequency of the workpiece is f 24 Hz, the diameter of its work surface is D 400 mm , the mass of the rolling mill m is 10.6 kg, its moment of inertia is I 0.54, the diameter of the machining rollers is D 10 mm, the diameter of the circle tangent to the machining rollers is DI 410 mm. As can be seen from the resulting graphic

From the range established by inequality (1), the number of rollers does not increase the hardness of the material of the machined part. An increase in E beyond the specified range can lead to the initiation of microcracks in the material of the workpiece, i.e. to re-camber it. Out of range to an increase in the number of rollers leads to a decrease in the degree of work hardening, a decrease in the thickness and hardness of the hardened layer,. Both in the first and in the second cases

five

0

50

five

0

five

0

five

712

the hardening efficiency of the part material and, consequently, its durability is reduced.

A device for carrying out the method (FIG. 3) comprises a platform 6 mounted on elastic elements 4 on base 5 with vibration exciter 7 with circular oscillations in a horizontal plane. Between the fixed stops 8 with balls 9 is mounted with the possibility of moving in the horizontal plane the shell of the lintel 2. On the case of the liner 2 on the axis x 10 evenly (Fig. 4) are machining bodies in the form of spherical polished rollers 3, with diameter D tangent to them circumference corresponds to (2), the number of rollers 3 is selected from the range defined by inequality (1), and the hardness of the material from which they are made is higher than the hardness of the material of the workpiece 1. The rotation axes of rollers 3 lie in radial The planes passing through the axis of the hull of the liner 2. When the cylindrical surfaces of the part 1 are strengthened, the rotation of each roller 3, which is its plane of symmetry, is offset relative to the plane of the adjacent roller 3 along the axis of the hull liner 2 up or down by an amount equal to (or less ) the width of the print b (Fig. 5). When machining conical surfaces, besides the specified axial displacement of the planes, there is a radial displacement of the axes of rotation of the adjacent rollers 3, determined by the taper value of the surface to be machined (Fig. 6). When machining curved surfaces, along with the indicated displacements, the angular displacement of the planes of rotation of the rollers 3, which are the planes of their symmetry, is performed (Fig. 7). The magnitude of these displacements is also determined by the size of prints b, which must overlap each other. In any of the above cases, the rollers 3- are installed in such a way that it is flat. The bone of their rotation is normal to the surface of the workpiece 1 at the point of contact. The axes of the workpiece 1 and the shell of the liner 2 are perpendicular to the plane of oscillation of the platform 6. Between the rollers 3 inside the shell of the liner 2 on the platform 6 there is a mandrel 11 with a nut 12 for fastening the part 1.

The surface of the part 1 is hardened on the device as follows.

The component 1 to be hardened is mounted on the mandrel 11 and rigidly fixed to the platform 6 with the help of a nut 12. The surface 1 of the component 1 is hardened inside the housing of the rolling-in device 2, opposite the rollers 3. The vibrator 7 is switched on, indicating to the platform 6 circular oscillations in its plane with a certain amplitude and frequency. The oscillations of the platform 6 are transmitted to the part 1 rigidly mounted on it. Under the influence of the oscillations of the part 1, the wheelhouse 2 is freely mounted between the supports 8 on the balls 9 and is vibrated to maintain the rotation and is brought into running-in over its surface. Contact of the body of the wrapper 2 with the surface of the part 1 takes place through the machining rollers 3. The coming into contact with the surface of the part 1 of each successive roller 3 during the rolling process

the annular body of the rolling-in device 2 of the Q-surface microhardness, determined with the help of the device PMT-3, on the sections made of the cut out areas of the hardened surface of the drums. At the same time, dressing the thin sections in Caller's solution, at a 120-fold magnification under an MMI-1 microscope, the nature of changes in the microstructure of the material of the hardened parts was observed. As a result of the experiment, it was found that as the number of machining rollers on the rolling wheel increases, the thickness of the hardened layer in the surface layer of the drum material decreases from 2.2 mm with n 3 to 0.5 mm with n 24, which is associated with a decrease with increasing number rollers energy impact collision with a drum. The surface microhardness of the material of the hardened drums decreases from 1475 MPa with n 3-6, to 1300 MPa with n 24, the degree of work hardening varies in the range of 0.2. 0.7. It is noted that in the range of variation of the number of rollers 6, the increase in surface microhardness is very insignificant (10%), and in the sublayer region of the hardened material of the drums,

It comes with a blow, and the colliding bodies are the massive workpiece 1 with platform 6 on the one hand, and the ring-on body of the rolling-in machine 2 tons on the other hand. The collision of the annular body of the wrapper 2 with the surface of the part 1 being processed when contacting them through the rollers 3 causes the material of the component 1 in its surface layer to be plastically deformed and strengthened at the points of contact with the rollers 3. The rotation of the ring body of the wrapper 2 and the specified location of the rollers 3 ensure the overlapping of the traces of collisions, thus achieving uniformity of hardening over the entire surface of the part 1 (Fig. 5-7). At the end of the processing time, the vibration exciter 6 is stopped, the nut 12 is unscrewed and the workpiece 1 is removed from the mandrel 11. In its place, the next part 1 to be hardened is fixed, fixed with a nut 12, and the processing cycle is repeated in the order described above.

According to the proposed method, a recess groove was machined.

ring drum type KT-14 IE aviation wheels, made of aluminum alloy AK6 with Brinell hardness HB 26.5. The treatment was carried out with the use of spherical machining parts with a diameter of 10 mm, made of ShKh15 steel and hardened to HRC55, fixed with rotation around its geometrical axis. The rollers were uniformly circumferential with a diameter of Dg 420 mm and mounted on a rolling edge with a mass m of 10.6 kg with a moment of inertia I 0.54 kg-m. The diameter of the circle, tangent to the rollers, D, 410 mm, and the diameter of the workpiece surface D 400 mm. Used experiment

0 changed the number of rollers on the roll-on bar from p 3 to p 24, leaving its mass and moment of inertia constant by attaching additional weights to the blader. Processing;

5 were made for 10 minutes,

with the frequency of oscillation of the part f 24 Hz and an amplitude of 3 mm. Strengthening quality control was performed by measuring the thickness of the hardened layer and

Q surface microhardness, defined0

five

0

five

molded with the help of the device PMT-3, on the thin sections made of the cut out sections of the hardened surface of the drums. At the same time, dressing the thin sections in Caller's solution, at a 120-fold magnification under an MMI-1 microscope, the nature of changes in the microstructure of the material of the hardened parts was observed. As a result of the experiment, it was found that as the number of machining rollers on the rolling wheel increases, the thickness of the hardened layer in the surface layer of the drum material decreases from 2.2 mm with n 3 to 0.5 mm with n 24, which is associated with a decrease with increasing number rollers energy impact collision with a drum. The surface microhardness of the material of the hardened drums decreases from 1475 MPa with n 3-6, to 1300 MPa with n 24, the degree of work hardening varies in the range of 0.2. 0.7. It is noted that in the range of change in the number of rollers 6, the increase in surface microhardness is very small (10%), and in the sublayer region of the hardened material of the drums, it was observed15152

The presence of microcracks, the appearance of which is associated, obviously, with the limited ability of the material of the drums to plastic deformation at large degrees of work hardening. The number of microcracks decreases as the number of rollers increases and disappears completely when n 7. When the number of rollers n 8, the thickness of the hardened layer in the material of the drums is 1.5 mm with its surface microhardness of 1450 MPa. The degree of work hardening is 0.5. With p 19, the thickness of the hardened layer in the material of the drums is 0.8 mm with its surface microhardness of 1350 MPa and the degree of work hardening of 0.3. With a further increase in the number of rollers to 24, the degree of work hardening decreases to 0.2, and the surface microhardness drops to 1300 MPa.

Experimental research results indicate that the number of rollers on the grinding wheel with the specified design parameters in the 8 in 19 range is optimal for hardening the reels. When this range goes down in the direction of decreasing the number of rollers, the microhardness does not increase significantly, and microcracks are formed in the material of the drum, indicating its re-curing. When out of range in the direction of increasing the number of rollers as a result of processing, the hardness of the material of the drums and the thickness of the hardened layer are not sufficiently developed. In both cases, the hardening treatment does not ensure the proper lifespan of the wheels of the aviation wheels.

The experimental data are consistent with the theoretical dependence (14) for determining the optimal number of rollers for hardening parts using the proposed method. Thus, it is necessary to ensure the degree of work hardening of 0.5 when hardening the drums from the alloy AK6 with the maximum impact energy Э, 10 -HB-D3, 5-10 "

J WwKC

(10-10 V 0.265 kg.m2 "2.6 J.

The number of rollers found from this inequality, corresponding to

E 2.6 j, n 7.3.

7 sixteen

Impact energy to ensure the degree of work hardening f. 0.3

, -2

Ech, mission 0.135-10 -HB-D 0.135-102 26.5- 10 (10 10) s - ::: 0.35. Ozh,

and the corresponding number of clips from (14) p 19.

Thus, the range of the number of rollers 7.3 6p 19, recommended by inequality (14), is very close to the experimentally established 8 n i19.

Claims (1)

In comparison with the known methods of hardening the details of the shape of rotation bodies, the proposed method provides an increase in the thickness and maximum hardness of the hardened layer, as well as the uniformity of hardening of surfaces on the local structural elements of details such as grooves and radius transitions, which is increased by pressure concentrators. motoresource details. Invention Formula The method of hardening parts, in which the part is installed with a gap in the body of the device, and the hardening is carried out by machining bodies placed between the surface to be machined and the body, while the processing is carried out in a vibration mode, in order to improve the quality of processing by increase the thickness and hardness of the hardened layer of the surface of the local structural elements of parts, the number of machining bodies is chosen from the range defined by the inequality , 135ЧО -НВ . D3 6 A (1 - -) J t sin , 2Jgn B + COS  i 10 -HB-D3 2 AT A, (1 + B); m is the moment of inertia and the body mass, respectively; 3ypiuH 0.5 25 A ( 9 3 JO 1 U 7 6 SCHCHCH $ SCH $$ $$ R  / 77f /) (/ 77 // ////////////////////////// ////////// / 5fig.z FIG.